British company offers efficient energy storage using ‘liquid air’

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One of the most significant challenges confronting the renewable energy market is the erratic output of wind and solar power stations. Modern power grids are designed to provide peak demand power in real time, not to store generated power until it’s needed. Wind and solar energy generation is tied to local environmental conditions, which is why some critics have argued that neither technology is reliable enough to replace conventional gas-fired turbines.

The UK company Highview Power Storage is challenging such claims, and has hard data to back up its position. For the past two years, Highview has operated a heat recovery and energy storage system at a working power plant in Buckinghamshire, England. Highview’s system is designed to take advantage of the fact that wind turbines continue spinning through the night, when electricity demand is far lower. At present, this additional generation is effectively wasted.

Highview’s system uses waste electricity to create liquid nitrogen (LN2, or what some have taken to calling liquid air). LN2 is created during the night and stored in high-pressure tanks. During the day, when peak demand is much higher, the LN2 can be brought back to room temperature. The gas expands as it warms and is used to turn a turbine. As the nitrogen returns to normal temperature, it’s re-captured by the Highview system, and the process can begin again.

The idea of a liquid nitrogen economy isn’t new, but Highview’s approach is much more efficient than other models proposed to date. The system is ~25% efficient on its own, but co-locating a Highview facility with a conventional power station allows the cryogenic system to use waste heat that’s created by its partner. By recapturing the nitrogen gas and making use of ambient waste heat, the company claims it can boost system efficiency as high as 70%. Currently, this low temperature (below 200 degrees C) air is simply pumped out and lost.

Highview’s system does for wind power what proposed molten salt energy storage does for solar panels. This type of storage could even be used to augment existing conventional plants by storing power produced at off-peak hours for peak usage. At present, power companies tend keep their oldest and least-efficient facilities in reserve to provide peak power. Studies have shown that even modest use of renewable energy can have a substantial impact on peak power rates and pollution levels. While not as efficient as batteries, there are numerous technical issues that prevent lithium-ion cells from being deployed on an industrial scale. At 70% efficiency, LN2 conversion could work as a potential alternative.

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Joel Detrow

Very clever as an energy storage method. Frankly, I’m surprised something so simple hadn’t already been implemented. I guess the main issue is that such a storage method assumes that some electricity generated from the wind farms actually goes to waste at night, rather than the companies simply ramping down main production and letting the wind pick up the slack. So, this technology would definitely be useful if/when an area gets more total power from wind than is used at all during the night. Not being well-versed in the subject, I can only guess.

Joel Hruska

Joel,

It only sounds simple at first glance. If you look at the structure, the liquid nitrogen recovery cycle is only 25% effective in and of itself. That’s pretty poor, and it’s why LN2 isn’t favored as a vehicle fuel.

It’s the waste heat recovery and use that makes the system efficient, and that’s a pretty new area of technology. If the process can go mainstream, it could possibly be deployed to effectively utilize waste heat energy in a number of companies.

GatzLoc

They could also use the LN2 to ‘overclock’ the wind turbines. :D

y666

This smells bullshit big time. You can use water for energy storage ( http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity ). It gives 70-80% effectiveness, is simple to implement and maintenance. Why anyone would choose overly complicated, poorly described, less effective idea over things already working for decades?

Besides system recovers 25% energy from liquid nitrogen (whatever it means for authors), and rest goes into waste heat. Trick is there’s no good technology to turn heat back into usable power (ie electricity), its peak effectiveness is maybe 50%. So we get 25% + 75% * 50%, which gives 62.5%, not 70%. My guess is authors don’t account for “free” energy from their partner, which makes everything cool in numbers, but useless in practice.

http://pulse.yahoo.com/_EKNZKJ5LBTYYEUH4NCSPTGFGGE Eric

Plus as the author writes, those numbers are only theoretical… calculated numbers…

“Currently, this low temperature (below 200 degrees C) air is simply pumped out and lost.” I don’t see ANYWHERE that this technology is installed and fully functional.

I see a pipe dream… or is that a pipe nightmare…

Any idea of the power required to pump high pressure gasses? It’s not pretty…

There are more numbers to add to the equation for the overall efficiency, and I am sure we will eventually learn that another technology easily surpasses this one.

cracking water for hydrogen and oxygen, to store, and later burn in a generator, can easily match this technology without the need for such high pressures or extreme temperatures… (Can you imagine the potential harm to employees if a line ruptured and sprayed liquid nitrogen all over?!!!)

how about the night time power is shunted to areas served by hydroelectric, like Hoover Dam, and lake water levels can be kept higher in drought conditions… Cities like Las Vegas use a huge amount of power day and night…. it’s not like wind power at night does not have a customer… This article makes an assumption that everyone turns off their heaters, lights, and TV’s at night….

I don’t buy it either…

CoBaja

I also think that this method is useless in practice. I wonder why don`t we use some primitive ways of energy collection first? After we reach the maximum then it would be nice to think about new methotd like “liquid air” and other. Did you know that one guy constructed primitive, 2KW solar panels for air heating, and he used old parts and recycled soda-cans? source: http://solar.freeonplate.com/diy-how-to/DIY-solar-panels.htm

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